This invention relates to an improved spring system which combines a tension spring function with a compression spring function that operate in response to the endwise movement of a plug extending through a two-section, coil spring.
Coil springs are commonly used for resiliently supporting or resiliently separating various types of articles or machine elements. Typically, the coil spring is arranged between a pair of relatively movable surfaces or elements which, upon moving together, compress the spring. Release of the pressure of the elements results in the spring resiliently returning to its initial size. The elements between which the spring is compressed, may comprise a plug-like member which fits within, and holds the coil spring and a support member. The two members are relatively movable; that is, one moves towards and away from the other.
This invention concerns forming the coil spring as an outer coil section which surrounds an inner coil section. The inner section is wrapped around a conically shaped plug so that endwise movement of the plug within the surrounding spring sections engages and resiliently stretches the inner coil section before the outer coil section compresses. This combines the effects of tension, due to the inner coil section, with compression provided by the outer coil section. This dual or composite coil spring arrangement provides a relatively compact, strong spring, as compared with conventional coil springs, which has many uses.